Rigid and semi-rigid liquid dispensing containers provide a convenient and cost effective way to dispense liquids, including caustic or liquid detergents, cleaning solutions, and other chemicals. One disadvantage of rigid or semi-rigid containers is that when liquid is dispensed, a vacuum can build in the container, which can cause one or more walls of the container to buckle or collapse. In some cases, the vacuum can also or instead limit or prevent liquid from properly dispensing from the container. In order to prevent a vacuum from forming as just described, air may be allowed into the container, such as when a volume of liquid is dispensed.
A cost effective way to allow air into the container is to provide a vent in a dispensing cap of the container. The vent typically comprises a one-way air valve permitting air to enter the container under sufficient vacuum, yet closing under all other conditions. However, such vents can be disabled from performing their air intake function in some orientations of the container. For example, in those container orientations in which a significant head of liquid is located over the air valve of the vent, the resulting head pressure can press the valve closed. Solutions to this problem include providing the valve with a pre-load to counter the force of the head pressure. However, as the amount of liquid in the container decreases, or as the orientation of the container changes, the head pressure can vary significantly, which can make conventional air vents prone to leakage. Another disadvantage of many air vents used for liquid containers is that elastomer components used in the valves of such vents can degrade and leak over time due to contact with contents of the container.
Based upon these and other limitations of conventional liquid container air vents and dispensing containers having such vents, improved air vents for liquid dispensing containers continue to be welcome in the art.